Function evaluator

evaluator(
evaluatorRef: string,
options?: Omit<ScenarioEvaluator, "evaluator">,
): ScenarioEvaluator
Attaches a LangWatch evaluator to a scenario run.
Parameters
- evaluatorRef: string
  A built-in type such as ragas/sql_query_equivalence, or a saved evaluator as evaluators/<slug>.
- options: Omit<ScenarioEvaluator, "evaluator"> = {}
  Whether the evaluator gates the run, its input mappings and its settings overrides. A mapping is a function of the scenario state or a literal. Unmapped inputs are inferred from their names.
Returns ScenarioEvaluator
Example
```
scenario.evaluator("ragas/sql_query_equivalence", {
  required: true,
  mappings: {
    output: (state) => state.toolCalls("run_sql").last?.input,
    expected_output: scenario.field("golden_sql"),
  },
});
```
- Defined in work/scenario/javascript/src/evaluators/mappings.ts:143